<h1 id="minnesota-congressional-districts">2020 Minnesota Congressional
Districts</h1>
<h2 id="redistricting-requirements">Redistricting requirements</h2>
<p>In Minnesota, districts must: 1. be convenient and contiguous (<a
href="https://www.revisor.mn.gov/constitution/#section_4_3">Minn. Const.
art. IV, § 3</a>) 2. be substantially equal in population (<a
href="https://www.revisor.mn.gov/statutes/2021/cite/2.91">Minn. Stat.
2.91</a>) 3. not divide political subdivisions more than necessary to
meet constitutional requirements (<a
href="https://www.revisor.mn.gov/statutes/2021/cite/2.91">Minn. Stat.
2.91</a>)</p>
<p>Furthermore, the following principles guide redistricting in
Minnesota which stipulate that districts must: 4. have populations as
nearly as equal as practical 5. preserve communities of interest 6. not
abridge voting rights of minority groups 7. not unduly protect nor
defeat incumbents (<a
href="https://www.mncourts.gov/mncourtsgov/media/CIOMediaLibrary/2011Redistricting/A110152Order9-12-11.pdf">Order
of the Special Redistricting Panel, Hippert vs. Ritchie,
No. A11-152</a>)</p>
<h3 id="algorithmic-constraints">Algorithmic Constraints</h3>
<p>We enforce a maximum population deviation of 0.1%. We use a
pseudo-county constraint described below which attempts to mimic the
norms in Minnesota of generally preserving county, city, and township
boundaries.</p>
<h2 id="data-sources">Data Sources</h2>
<p>Data for Minnesota comes from the ALARM Project’s <a
href="https://alarm-redist.github.io/posts/2021-08-10-census-2020/">2020
Redistricting Data Files</a>. Data for Minnesota’s 2020 congressional
district map comes from the Minnesota Legislature’s <a
href="https://gis.lcc.mn.gov/redist2020/cong20.php?plname=C2022&amp;pltype=court">Geographic
Information Services</a></p>
<h2 id="pre-processing-notes">Pre-processing Notes</h2>
<p>No manual pre-processing decisions were necessary.</p>
<h2 id="simulation-notes">Simulation Notes</h2>
<p>We sample 5,000 districting plans for Minnesota across two
independent runs of the SMC algorithm. We use a pseudo-county constraint
to limit the county and municipality (i.e., city and township) splits.
Municipality lines are used in Anoka County, Dakota County, Hennepin
County, and Ramsey County, which are all counties with populations
larger than 40% the target population for a district.</p>
<h2 id="contents">Contents</h2>
<ul>
<li><code>MN_cd_2020_stats.csv</code> contains summary statistics on the
sampled redistricting plans</li>
<li><code>MN_cd_2020_plans.rds</code> is a compressed
<code>redist_plans</code> object, which contains the matrix of
precinct/block assignments and may be used for further analysis.</li>
<li><code>MN_cd_2020_map.rds</code> is a compressed
<code>redist_map</code> object, which contains the precinct/block
shapefile and demographic data.</li>
</ul>
<p>Both the <code>redist_plans</code> and <code>redist_map</code> object
are intended to be used with the <a
href="https://alarm-redist.github.io/redist/">redist package</a>.</p>
<h3 id="codebook-for-summary-statistics">Codebook for summary
statistics</h3>
<ul>
<li><code>draw</code>: unique identifier for each sample. Non-numeric
draw names are real-world plans, e.g., <code>cd_2010</code> for an
enacted 2010 plan.</li>
<li><code>district</code>: a district identifier. District numbers
roughly match those in the enacted plan, but the correspondence is not
perfect.</li>
<li><code>chain</code>: a number identifying the run of the
redistricting algorithm used to produce this draw. Used for diagnostic
purposes.</li>
<li><code>pop_overlap</code>: a number indicating the fraction of people
in this plan who reside in the same-numbered district in the enacted
plan.</li>
<li><code>total_pop</code>: the total population of each district.</li>
<li><code>total_vap</code>: the total voting-aged population of each
district.</li>
<li><code>pop_*</code>, <code>vap_*</code>: total (voting-aged)
population within racial and ethnic groups for each district. Variable
codes documented <a
href="https://github.com/alarm-redist/census-2020#data-format">here</a>.</li>
<li><code>plan_dev</code>: the maximum population deviation among
districts in the plan. Computed as
<code>max(abs(distr_pop - target_pop)/target_pop)</code>.</li>
<li><code>comp_edge</code>: compactness, as measured by the fraction of
internal edges kept. Higher values indicate more compactness.</li>
<li><code>comp_polsby</code>: compactness, as measured by the
Polsby-Popper score. Higher values indicate more compactness.</li>
<li><code>county_splits</code>: the number of counties which belong to
more than one district.</li>
<li><code>muni_splits</code>: the number of Census Designated Places
which belong to more than one district.</li>
<li><code>*_##_dem_*</code>, <code>*_##_rep_*</code>: vote counts for
statewide Democratic and Republican candidates in a certain election.
More information <a
href="https://github.com/alarm-redist/census-2020#data-format">here</a>.</li>
<li><code>adv_##</code>, <code>arv_##</code>: average vote counts for
statewide Democratic and Republican candidates in a certain year. More
information <a
href="https://github.com/alarm-redist/census-2020#data-format">here</a>.</li>
<li><code>ndv</code>, <code>nrv</code>: averages of the
<code>adv_##</code> and <code>arv_##</code> variables across all
available elections.</li>
<li><code>ndshare</code>: normal Democratic share, computed as
<code>ndv / (ndv + nrv)</code></li>
<li><code>e_dvs</code>: average Democratic vote share, computed as the
average of the Democratic vote share when first scored under each
statewide election.</li>
<li><code>pr_dem</code>: probability seat is represented by a Democrat;
calculated as the fraction of statewide elections under which the
district had a majority Democratic share.</li>
<li><code>e_dem</code>: expected number of Democratic seats for the
plan; equivalent to summing the <code>pr_dem</code> values across
districts</li>
<li><code>pbias</code>: partisan bias at 50% vote share, averaged across
all available elections. Positive values indicate Republican bias.</li>
<li><code>egap</code>: the efficiency gap, averaged across all available
elections. Positive values indicate Republican bias.</li>
</ul>
